| 摘要 |
PURPOSE:To accurately detect the rotating state of a vibration wave motor and to accurately control the rotating speed or angle by forming a rotation detector in a noncontact type using the interference of a light. CONSTITUTION:A light beam from a coherence light source 8 becomes a substantially parallel beam by a collimator lens 9, and is input to a beam splitter 10. Reflected and transmitted lights divided at the splitter are directed to a diffraction grating 7 as two beam through reflecting mirrors 111, 112. In this case, its incident angle thetam is expressed by a formula (I), where (m) is an integer, (lambda) is the wavelength of a coherent light source 8, and (p) is the lattice pitch of the grating 7. Assume that the total number of the lattices of the lattice 7 is 21600, 43200 of sine waves of twice as large as the total number of the gratings are obtained from a photodetector 12 by one revolution of a rotor 6. The output signal of the photodetector 12 is fed back to a driving circuit for a vibration wave motor to accurately control its speed or angle. |
